302 38. LECANORACEAE [142. Lecanora 



subsessile, the disk flat to convex, yellowish to brownish black, commonly greenish 

 to whitish pruinose, the exciple thick, colored like the thallus, becoming flexuous 

 and crenulate; spores ovoid-ellipsoid, 12-16 X 6.5-10//.. 



On trees and rarely on rocks, California, Oregon, and Washington. 



28. Lecanora Hageni Ach., Lich. Univ. 367. 1810. 



Lichen Hageni Ach., Lich. Suec. 57. 1798. L. Hageni var. umbrina Ach. 



Thallus thin, smooth, becoming warty, the warts sometimes scattered, or rarely 

 disappearing, dirty greenish to ashy white; apothecia small to middle-sized, 0.4-1 

 mm. across, adnate, the disk flat to slightly convex, more or less grayish pruinose 

 or pale brown to blackish, the exciple white or colored like the thallus, usually 

 more or less crenate, rarely flexuous or disappearing; spores ellipsoid, 7-14 X 4-6 fi. 



On trees, old wood, and rocks, throughout the United States. 



29. Lecanora Sambuci (Pers.) Nyl., Not. Sallsk. Faun. Flor. Fenn. 5:168. 1861. 

 Lichen Sambuci Pers., Ann. Bot. Usteri 7:26. 1794. L. Hageni var. Sambuci 



(Pers.) Tuck. 



Thallus thin, smooth, becoming granulose to minutely scaly, whitish to ashy 

 gray, rarely disappearing; apothecia minute to small, 0.3-1 mm. across, adnate, the 

 disk flat to slightly convex, flesh-colored to light brown or darker, often grayish 

 pruinose, the exciple thin, colored like the thallus, becoming crenulate and rarely 

 disappearing; spores 8-32, usually 12-16, ellipsoid, 8-12 X 4.5-6.5 [x. 



On trees, Massachusetts, Illinois, and Minnesota. 



var. minnesotensis Fink; Hedrick, Mycologia 26:161. 1934. 

 Exciple becoming flexuous and disappearing, the disk in this condition strongly 

 convex and broken into 2 to 8 convex areas, giving the appearance of as many 

 very minute conglomerate apothecia. 



On balsam trunks, Grand Portage, Minnesota. 



30. Lecanora praecrenata Nyl., in Hasse, Lich. South. Calif. 12. 1898. 

 Thallus very thin, dirty white, disappearing; apothecia small, 0.5-0.8 mm. 



across, sessile, the disk flat, dusky brown, the exciple slightly elevated, colored like 

 the thallus, crenulate, the crenules globose, necklace-like; spores 4-6, spherical, 

 18-21 fi in diameter. 



On rocks, southern California. 



31. Lecanora Willeyi Tuck., Syn. N. A. Lich. 1:191. 1882. 



Thallus very thin, warty, rough and heaped, dark greenish gray to ashy; apo- 

 thecia minute to small, 0.3-0.8 mm. across, adnate, the disk flat to strongly convex, 

 dark red, the exciple thin, colored like the thallus or olive-green, becoming crenu- 

 late, sometimes disappearing; spores ellipsoid, 8-11 X 4— 7 fx. 



On rocks, Massachusetts and New Jersey. 



32. Lecanora piniperda Koerb., Par. Lich. 81. 1865. 



Thallus thin, becoming scurfy or somewhat warty or granulose, greenish gray 

 to whitish, often disappearing; apothecia minute, 0.1-0.25 mm. across, adnate, the 

 disk flat to convex, flesh-colored to brownish, often obscurely pruinose, the exciple 

 usually thin, colored like the thallus or lighter, becoming subcrenulate, often dis- 

 appearing; spores ellipsoid, 8-12 X 4-5.5 fx. 



On stumps, Ohio and Minnesota. 



33. Lecanora dispersa (Pers.) Rohl., Deutschl. FI. 3:91. 1813. 

 Lichen dispersus Pers., Ann. Bot. Usteri 7:27. 1794. 



Thallus composed of small, scattered, dirty greenish to whitish granules, some- 

 times persisting under the apothecia but disappearing elsewhere; apothecia minute 

 to small, 0.3-1.2 mm. across, often clustered, adnate, the disk flat, yellowish brown 

 to olivaceous, the exciple thin, colored like the thallus, more or less crenate; 

 spores ellipsoid, 8-13 X 3.5-5.5 fx. 



On rocks, Ohio, Iowa, and Minnesota. 



